1. Field of the Invention
The present invention relates to a steering lock system in which an actuator section for locking or unlocking a steering shaft is separated from an operation section such as a key device.
2. Related Art
An existing steering lock system comprises a key section which is mechanically actuated in association with a lock mechanism of the steering shaft and is formed into an integral unit. With regard to the common structure of the steering lock system, a cam member which rotates together with a key rotor in an integrated manner extends to a lock mechanism between the key rotor and the lock mechanism of a steering shaft while remaining in a concentric position relative to the key rotor. In addition, a locking lever which is actuated in association with the insertion and removal of a key is interposed between the key rotor and the lock mechanism. When the key is turned from an "ACC" position to a "LOCK" position, the cam member is actuated. In response to the actuation of the cam member, the lock member provided in the lock mechanism of the steering shaft is also actuated so as to be able to lock the steering shaft. If the key is removed from the key rotor while the rotor is in the "LOCK" position, the locking lever is actuated, which in turn actuates the lock member so as to fit into the groove of the steering shaft, thereby locking the steering shaft.
The key is inserted into the key rotor while the rotor is in the "LOCK" position and is then turned to an operating position (e.g., "ACC," "ON," or "START" position), the cam member is actuated to thereby move the lock member to an unlock position.
However, with the foregoing configuration, the key section and the lock mechanism of the steering shaft are assembled as a unit to mechanically move in association with each other. If the key section is provided in an instrument panel in the vicinity of the driver's seat, the lock mechanism is positioned in front of the driver's knees. As a result, the strength or position of the lock mechanism may be limited.
To solve this problem, it is thought that an operation section, such as a key device, is separated from an actuator section of the lock mechanism, or the like. In this case, the lock member incorporated in the lock mechanism is moved to the lock position by means of a spring member. In a case where the key is inserted into the key rotor and turned to the "ACC" position (i.e., a case where the lock mechanism is unlocked), the turning action is detected, for example, by detection means. In accordance with a detection signal, drive means, such as a motor, is driven so as to move the lock member to the unlock position.
Here, if the lock member is engaged with the lock groove of the steering shaft or undergoes so-called handle torque, the degree of fitting of the lock member into the groove is increased. As a result, the lock member may not move toward the unlock position at all even if the motor is turned on. In such a case, the handle is slightly turned so as to eliminate the handle torque, and the motor is turned on again. In the end, the lock member may become disengaged from the lock groove. In this case, however, the motor locks at the beginning, which in turn results in labor for turning on the motor twice. A reduction in the useful life of the motor may also result.
Incidentally, there is a need for means for holding the lock member in the unlock position in order to prevent the lock member from inadvertently locking the steering shaft. Since the existing lock mechanism of the steering shaft is mechanically actuated in association with the key, the lock member is held in the unlock position by means of the cam member, so long as the key rotor is situated in a predetermined turn position.
In the case of the aforementioned lock mechanism, in which the operation section such as a key device is separated from the actuator section of the lock mechanism, means for holding the lock member in the unlock position must be newly provided for the actuator section, because the lock mechanism does not have any cam member. To this end, an unlock-status hold member is attached to electric drive means; e.g., a plunger of a solenoid, and an electric signal is produced by actuation of the operation section. The solenoid is actuated by the electrical signal, thereby holding the lock member in the unlock position by means of the unlock-status hold member.
In the case of such a configuration in which the unlock-status hold member is actuated by means of the electrical drive means such as a solenoid, fears arise as to operation failures due to electrical problems.